﻿// <copyright file="RelayCommand.cs" company="GalaSoft Laurent Bugnion">
// Copyright © GalaSoft Laurent Bugnion 2009-2011
// </copyright>
// ****************************************************************************
// <author>Laurent Bugnion</author>
// <email>laurent@galasoft.ch</email>
// <date>22.4.2009</date>
// <project>GalaSoft.MvvmLight</project>
// <web>http://www.galasoft.ch</web>
// <license>
// See license.txt in this project or http://www.galasoft.ch/license_MIT.txt
// </license>
// <LastBaseLevel>BL0008</LastBaseLevel>
// ****************************************************************************
// <credits>This class was developed by Josh Smith (http://joshsmithonwpf.wordpress.com) and
// slightly modified with his permission.</credits>
// ****************************************************************************

using System;
using System.Diagnostics;
using System.Diagnostics.CodeAnalysis;
using System.Windows.Input;

////using GalaSoft.Utilities.Attributes;

namespace HanumanInstitute.MediaPlayer.Wpf.Mvvm;

/// <summary>
/// A command whose sole purpose is to relay its functionality to other
/// objects by invoking delegates. The default return value for the CanExecute
/// method is 'true'.  This class does not allow you to accept command parameters in the
/// Execute and CanExecute callback methods.
/// </summary>
////[ClassInfo(typeof(RelayCommand),
////  VersionString = "3.0.0.0",
////  DateString = "201003041420",
////  Description = "A command whose sole purpose is to relay its functionality to other objects by invoking delegates.",
////  UrlContacts = "http://www.galasoft.ch/contact_en.html",
////  Email = "laurent@galasoft.ch")]
public class RelayCommand : ICommand
{
    private readonly Action _execute;

    private readonly Func<bool>? _canExecute;

    /// <summary>
    /// Initializes a new instance of the RelayCommand class that 
    /// can always execute.
    /// </summary>
    /// <param name="execute">The execution logic.</param>
    /// <exception cref="ArgumentNullException">If the execute argument is null.</exception>
    public RelayCommand(Action execute)
        : this(execute, null)
    {
    }

    /// <summary>
    /// Initializes a new instance of the RelayCommand class.
    /// </summary>
    /// <param name="execute">The execution logic.</param>
    /// <param name="canExecute">The execution status logic.</param>
    /// <exception cref="ArgumentNullException">If the execute argument is null.</exception>
    public RelayCommand(Action execute, Func<bool>? canExecute)
    {
        execute.CheckNotNull(nameof(execute));

        _execute = execute;
        _canExecute = canExecute;
    }

#if SILVERLIGHT
        /// <summary>
        /// Occurs when changes occur that affect whether the command should execute.
        /// </summary>
        public event EventHandler CanExecuteChanged;
#else
    /// <summary>
    /// Occurs when changes occur that affect whether the command should execute.
    /// </summary>
    public event EventHandler CanExecuteChanged
    {
        add
        {
            if (_canExecute != null)
            {
                CommandManager.RequerySuggested += value;
            }
        }

        remove
        {
            if (_canExecute != null)
            {
                CommandManager.RequerySuggested -= value;
            }
        }
    }
#endif

    /// <summary>
    /// Raises the <see cref="CanExecuteChanged" /> event.
    /// </summary>
    [SuppressMessage("Microsoft.Performance", "CA1822:MarkMembersAsStatic",
        Justification = "The this keyword is used in the Silverlight version")]
    [SuppressMessage("Microsoft.Design", "CA1030:UseEventsWhereAppropriate",
        Justification = "This cannot be an event")]
    public void RaiseCanExecuteChanged()
    {
#if SILVERLIGHT
            var handler = CanExecuteChanged;
            if (handler != null)
            {
                handler(this, EventArgs.Empty);
            }
#else
        CommandManager.InvalidateRequerySuggested();
#endif
    }

    /// <summary>
    /// Defines the method that determines whether the command can execute in its current state.
    /// </summary>
    /// <param name="parameter">This parameter will always be ignored.</param>
    /// <returns>true if this command can be executed; otherwise, false.</returns>
    [DebuggerStepThrough]
    public bool CanExecute(object parameter) =>
        _canExecute == null || _canExecute();

    /// <summary>
    /// Defines the method to be called when the command is invoked. 
    /// </summary>
    /// <param name="parameter">This parameter will always be ignored.</param>
    public void Execute(object parameter) => _execute();
}
